We don't see clear symptoms of rust disease on either plant (the spores that give the disease its "rust" name are pretty unique-looking), but various other leaf infections can cause spotting and premature leaf shed. Often, they are not serious or life-threatening to the plant. Weather plays a large role in disease spread and severity as well, so a damaging outbreak one year doesn't guarantee it will occur again the next, though your clean-up of fallen foliage is prudent. Many bush snap bean varieties happen to be suitably resistant to rust infection. (None are immune, but the disease is rarely seen.) This University of Connecticut blog post discusses rust on beans, and while it includes some technical details about the fungus' life cycle, it also provides a couple of sample images of leaf symptoms: https://uconnladybug.wordpress.com/2016/09/29/bean-frecklesaka-bean-rust/

While we can't identify the exact cause of the leaf spots on the Hibiscus, it does not look serious and should not measurably reduce the vigor of the plant by itself. Other growing conditions would likely have a greater impact on its health and appearance over the long term. Perennial Hibiscus need to stay moist (or, at least, not dry out completely for long) when grown in containers. If this plant is in a pot and not in the ground, check it periodically during the winter to make sure it's not getting too dry, and water it well (as needed) during thaws. If being grown in a container long-term, you'll also need to fertilize once in awhile as nutrients get used-up or leached out of the pot; frequency of fertilization depends on the pot size and type of fertilizer product used, but the product label should provide instructions or guidance. When the roots run out of growing room, as they tend to in a container, that may stunt the top growth and prevent the plant from becoming as dense and full as it would in the ground. This is not a health problem per se, but can contribute to a lanky, leggy (bare-bottomed) look over time if a recurring minor leaf infection causes some mid-season defoliation in future seasons.

Neem oil can be useful as a topical low-toxicity insecticide for certain insect or mite pests, but it isn't a very effective broad-spectrum fungicide. Although several fungicide product options should be easy to find at garden centers, none is warranted at this point since the disease impacts are minimal; excessive fungicide use in general can negatively impact harmless soil organisms and other wildlife, so we discourage their use when not necessary.

For now, you don't need to do anything else except to continue to monitor the plant for water needs. As the weather cools and the plant goes dormant (losing leaves, and the above-ground stems will die), its water needs will decrease. Hibiscus sprout quite late in spring, so if this is your first time overwintering the plant, just be aware that you may not see signs of new growth until sometime in mid-May or so, depending on the weather.

Miri

Insulation might be improved if you use unopened bags of mulch (or compost, bales of straw...anything with mass/volume to retain warmth). Plastic around the pot probably won't do much, even with newspaper filler, but more importantly the pot needs to be open to precipitation (or able to be watered) and must drain freely so the soil doesn't become oversaturated.

Miri